Daptomycin In Vitro Activity against Methicillin-Resistant Staphylococcus aureus Is Enhanced by d-Cycloserine in a Mechanism Associated with a Decrease in Cell Surface Charge.

The killing activity of daptomycin against an isogenic pair of daptomycin-susceptible and daptomycin-nonsusceptible (DNS) methicillin-resistant Staphylococcus aureus (MRSA) strains was enhanced by the addition of certain cell wall agents at 1× MIC. However, when high inocula of the DNS strain were used, no significant killing was observed in our experiments. Cytochrome c binding assays revealed d-cycloserine as the only agent associated with a reduction in the cell surface charge for both strains at the concentrations used.

Utility of peptide nucleic acid fluorescence in situ hybridization for rapid detection of Acinetobacter spp. and Pseudomonas aeruginosa.

The utility of peptide nucleic acid fluorescence in situ hybridization (PNA FISH) for the detection of Acinetobacter spp. and Pseudomonas aeruginosa was evaluated on broth suspensions and spiked blood cultures of ATCC strains and clinical isolates with select gram-negative rods. After testing 60 clinical isolates, PNA FISH had a sensitivity and specificity of 100% and 100%, respectively, for Acinetobacter spp. and 100% and 95%, respectively, for P. aeruginosa. PNA FISH was able to detect both pathogens simultaneously and directly from spiked blood cultures.

Functional, molecular and proteomic characterisation of bone marrow mesenchymal stem cells in rheumatoid arthritis.

OBJECTIVE: Bone marrow (BM) mesenchymal stem cells (MSCs) are being considered as potential therapeutic agents in various inflammatory autoimmune diseases for their tissue-repair and anti-inflammatory tissue-protective properties. This study investigates the reserves and function, the molecular and proteomic profile and the differentiation potential of BM MSCs in patients with active rheumatoid arthritis (RA). METHODS: We evaluated the frequency of MSCs in the BM mononuclear cell fraction using a limiting dilution assay, the proliferative/clonogenic potential and the capacity of cells to differentiate towards the osteogenic/chondrogenic/adipogenic lineages using appropriate culture conditions. We also assessed the molecular and proteomic characteristics in terms of inflammatory cytokine gene and protein expression, the relative telomere length and the survival characteristics of BM MSCs. RESULTS: MSCs from patients with RA (n = 26) and age- and sex-matched healthy individuals (n = 21) were similar in frequency, differentiation potential, survival, immunophenotypic characteristics, and protein profile. Patient MSCs, however, had impaired clonogenic and proliferative potential in association with premature telomere length loss. Transcriptome analysis revealed differential expression of genes related to cell adhesion processes and cell cycle progression beyond the G1 phase. Previous treatment with methotrexate, corticosteroids, anti-cytokine and biological agents or other disease-modifying anti-inflammatory drugs did not correlate with the clonogenic and proliferative impairment of BM MSCs. CONCLUSION: In spite of some restrictions related to the impaired clonogenic and proliferative potential, our findings support the use of autologous BM MSCs in RA and may have important implications for the ongoing efforts to repair tissue injury commonly seen in the course of the disease.

Changes in maternal plasma levels of VEGF, bFGF, TGF-beta1, ET-1 and sKL during uncomplicated pregnancy, hypertensive pregnancy and gestational diabetes.

BACKGROUND: Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), transforming growth factor-beta1 (TGF-beta1), endothelin-1 (ET-1) and soluble c-kit ligand (sKL) are cytokines involved in embryogenesis. MATERIALS AND METHODS: Maternal plasma cytokines were measured with ELISA during the three trimesters of gestation and on the day of delivery in 93 pregnant women and 18 age-matched non-pregnant control women. RESULTS: The VEGF and bFGF levels increased during the first trimester and declined thereafter, but they remained above the controls' values until delivery. The TGF-beta1 levels increased during the first trimester and remained unchanged thereafter. On the contrary, the ET-1 levels decreased and remained low until delivery. VEGF, bFGF, TGF-beta1 and ET-1 were increased in hypertensive pregnancy. Except for ET-1, these cytokines were also increased in gestational diabetes. No changes in plasma sKL were documented. CONCLUSION: All the aforementioned cytokines play a role in uncomplicated pregnancy, whereas hypertensive pregnancy is causatively-related with increased ET-1.

Normal bone marrow hematopoietic stem cell reserves and normal stromal cell function support the use of autologous stem cell transplantation in patients with multiple sclerosis.

Bone marrow (BM) stem cell reserves and function and stromal cell hematopoiesis supporting capacity were evaluated in 15 patients with multiple sclerosis (MS) and 61 normal controls using flow cytometry, clonogenic assays, long-term BM cultures (LTBMCs) and enzyme-linked immunosorbent assays. MS patients displayed normal CD34+ cell numbers but a low frequency of colony-forming cells (CFCs) in both BM mononuclear and purified CD34+ cell fractions, compared to controls. Patients had increased proportions of activated BM CD3+/HLA-DR+ and CD3+/CD38+ T cells that correlated inversely with CFC numbers. Patient BM CD3+ T cells inhibited colony formation by normal CD34+ cells and patient CFC numbers increased significantly following immunomagnetic removal of T cells from BMMCs, suggesting that activated T cells may be involved in the defective clonogenic potential of hematopoietic progenitors. Patient BM stromal cells displayed normal hematopoiesis supporting capacity indicated by the CFC number in the nonadherent cell fraction of LTBMCs recharged with normal CD34+ cells. Culture supernatants displayed normal stromal derived factor-1 and stem cell factor/kit ligand but increased flt-3 ligand levels. These findings provide support for the use of autologous stem cell transplantation in MS patients. The low clonogenic potential of BM hematopoietic progenitors probably reflects the presence of activated T cells rather than an intrinsic defect.

Fever and urticaria in acute giardiasis.

Travelers' diarrhea afflicts some 250 million people yearly. A number of etiologic agents have been identified, including bacteria, viruses, and parasites. Giardia lamblia is one of the pathogens clearly associated with this syndrome. Typical symptoms of giardiasis that include abdominal bloating and cramps are well known, whereas urticaria has rarely been associated with this illness. An American tourist developed acute giardiasis accompanied by urticaria and high fever. No other pathogens were identified, and response to metronidazole therapy was prompt. Giardiasis should be included in the differential diagnosis of acute urticaria and fever in the traveler.

Triiodothyronine-induced thyrotoxicosis in ophthalmic Graves disease.

A euthyroid woman with ophthalmic Graves disease developed endogenous hyperthyroidism coincident with T3 suppression test. There is a putative role of liothyronine administration in precipitating or activating hyperthyroidism. Aberrancies in T3 suppression testing in graves disease occur.

Pseudallescheria boydii infection of the central nervous system.

Pseudallescheria boydii is a rare cause of central nervous system infection characteristically presenting as a neutrophilic meningitis or multiple brain abscesses. Factors predisposing to central nervous system infection with this fungus include immunosuppression and near drowning. The organism is infrequently cultured from fluid obtained by lumbar puncture, delaying clinical recognition and appropriate antifungal therapy. All untreated patients with P boydii infection of the central nervous system died. We describe a patient who developed a persistent neutrophilic meningitis with focal neurologic deficits due to P boydii 6 months after a freshwater aspiration pneumonia. We also review the characteristic clinical and pathologic features of previously reported cases and emphasize the importance of early detection and treatment in the management of this frequently intractable disease.

Ciprofloxacin in combination with other antimicrobials.

Combinations of ciprofloxacin with aminoglycosides or beta-lactams are infrequently synergistic and only rarely antagonistic against Enterobacteriaceae or gram-positive bacteria. Against Pseudomonas aeruginosa, combinations of ciprofloxacin with an aminoglycoside are synergistic for a minority of isolates, whereas rates of synergistic interactions between ciprofloxacin and beta-lactams against this group of organisms vary over a wide range.

Beta-lactam/aminoglycoside combinations: interactions and their mechanisms.

Combinations of beta-lactams with aminoglycosides are widely used in the therapy of infections. There are a number of theoretic advantages to using such combinations. Indeed, combinations of beta-lactams and aminoglycosides usually result in synergism or indifference and very rarely in antagonism. The mechanisms of synergism, resistance to synergism, and antagonism have been studied extensively in enterococci; further studies are necessary to define such mechanisms in other organisms.

In vitro activity of fluoroquinolones against gram-positive bacteria.

This paper reviews the in vitro activities of several newer fluoroquinolone antimicrobials that exhibit enhanced potency against Gram-positive bacteria. Several of these agents demonstrate 10-fold greater activity than older members of this class against Staphylococcus aureus and inhibit [minimum inhibitory concentration (MIC90) values < or = 2 mg/L] many isolates resistant to ciprofloxacin or ofloxacin. Markedly enhanced activity is also noted against Streptococcus pneumoniae, 90% of isolates being inhibited at concentrations 10- to 100-fold lower than those of the older agents. Enterococci also exhibit greater susceptibility to several of the newer fluoroquinolones, although relative cross-resistance with the earlier drugs is noted. As determined by dilution techniques, the new fluoroquinolones generally demonstrate bactericidal activity at concentrations at or near their MIC values. The activities of the new compounds described here are decreased at low pH, but are not affected by the addition of up to 50% human serum to the test medium. Resistance is rarely detected (frequency < 10(-9)) when high density bacterial suspensions are plated in the presence of 4 times the MIC of these compounds. However, colonies displaying relative resistance to the new agents can be selected by serial passage in incremental antimicrobial concentrations.

Activity of newer fluoroquinolones in vitro against gram-positive bacteria.

Several newer fluoroquinolones, which have been recently introduced or are under investigation, display substantially greater potency against gram-positive organisms than the older generation agents of this class. Nevertheless, for problem organisms including methicillin-resistant strains of Staphylococcus aureus and many Enterococcus faecium, concentrations of newer antimicrobials required to inhibit 90% of organisms in the collections studied remain above those that are projected to be achievable with clinical use. Nevertheless, enhanced potency of several newer quinolones may result in a favourable pharmacodynamic profile leading to improved outcomes against gram-positive infections and possibly to the delayed or diminished emergence of resistance to these agents.

'Fetal' erythropoiesis following bone marrow transplantation as estimated by the number of F cells in the peripheral blood.

The aim of this study was to define factor(s) influencing fetal erythropoiesis following bone marrow transplantation. Thirty-one transplanted patients (14 males, 17 females) were studied. The underlying diseases were chronic myelogenous leukaemia (CML, 18 patients), acute myeloblastic leukaemia (AML, 7 patients) and acute lymphoblastic leukaemia (ALL, 6 patients). Reticulocyte and peripheral F cell estimation was carried out in donors and patients before transplantation and repeatedly during recovery. For F cell estimation, an indirect immunofluorescence assay was utilized. A significant increase above pre-BMT values in the percentage of F cells was observed in all patients from days 11 to 40 after transplantation. The increase of F cells on days 15, 18, 25, 32, 40 and 50 after transplantation was statistically significant in 14 patients who had shown an increase of F cells following chemotherapy (high responders) compared with the remaining 17 patients who did not respond so significantly. This finding supports the influence of the host bone marrow micro environment. The nature of the mechanisms operating remains to determined.

Vancomycin-resistant Enterococcus faecium in hospitalized children.

OBJECTIVE: Determine the epidemiology and risk factors for colonization with vancomycin-resistant Enterococcus faecium. DESIGN: Survey; case-control study. SETTING: Children's hospital. PATIENTS: Pediatric oncology patients. INTERVENTION: Contact isolation, restriction of vancomycin prescribing. RESULTS: There was a high prevalence of colonization with vancomycin-resistant enterococci among pediatric oncology patients. The length of hospitalization and the administration of vancomycin and other intravenous antibiotics was associated with colonization. Prevention of colonization was associated with restriction of vancomycin use and contact isolation. CONCLUSIONS: Vancomycin use may predispose to colonization with vancomycin-resistant E faecium. Vancomycin-resistant E faecium may be nosocomially spread. Contact isolation and restriction of vancomycin use may prevent spread of vancomycin-resistant E faecium.

An unusual case of splenic abscess and sepsis in an immunocompromised host.

Lactobacilli are important members of the vaginal, gastrointestinal, and oral flora in humans. Although these organisms are usually innocuous, increasing numbers of serious infections attributable to these bacilli have recently been reported. The authors report an unusual case of a patient presenting with a splenic abscess and sepsis resulting from lactobacilli and review the literature describing serious infections caused by these organisms.

Expression of p53, p21/waf1, bcl-2, bax, Rb and Ki67 proteins in Hodgkin's lymphomas.

The aim was to investigate the combined immunoexpression of p53, p21, bcl-2, bax, Rb and Ki67 proteins in Hodgkin's lymphomas (HL) and correlate expression patterns with the histotype and the Epstein-Barr Virus (EBV) status. Paraffin-sections from 56 cases of HL (18 nodular sclerosis and 38 mixed cellularity) and from ten "reactive" lymph nodes were investigated. P53, p21, bcl-2, bax, Rb and Ki67 proteins were detected in Hodgkin and Reed-Sternberg (HRS) cells in 35/56, 56/56, 24/56, 23/56, 56/56 and 56/56 cases of HL, respectively. No correlation was found between the expression of each protein and the EBV status or the histotype of HL. Comparison between p53 and p21 staining revealed two patterns: a) p53+/p21+ (35 cases); and b) p53-/p21+ (21 cases). The pattern p53+/p21+ suggests wild type p53 protein able to induce the expression of p21 while the p53-/p21+ pattern suggests p53-independent p21 expression. These results are consistent with the interpretation that inactivating p53 gene mutations may be rare in HL. Comparison between bcl-2 and bax staining showed a statistically significant relationship (p<0.001) for coexpression (19 cases) or absence of expression of both proteins (28 cases) in HRS cells. In contrast, bax expression was observed in most lymphoid cells in all "reactive" lymph nodes. Since the proapoptotic bax protein may act as tumour suppressor it is possible that the absence of this protein in HRS cells in a substantial proportion of HL may confer growth advantage and play a role in their pathogenesis. This could suggest bax gene alterations in some HL since in other studies acute lymphoblastic leukaemia cell lines demonstrate bax gene mutations with loss of bax immunoexpression. Another possibility is that reduced bax expression may be due to post transcriptional regulation, as was described in lymphoma cell lines. Comparison between Rb and Ki67 staining disclosed two main deviations from the normal parallel relationship in reactive lymph nodes: a) 2 cases with low Rb and high Ki67 expression possibly reflecting loss of Rb expression due to chromosome loss or to other abnormalities in the structure or the expression of Rb gene; and b) 9 cases with high RB and low Ki67 possible reflecting an attempt of Rb protein in excess to induce cell cycle arrest. Taken together, our findings provide combined immunohistological evidence for deregulated expression of cell-cycle and apoptosis-related proteins, that may play a role in the pathogenesis of HL.

Synergism and antagonism.

Among the reasons for use of antimicrobials in combination is the desire to achieve synergistic inhibitory or bactericidal activity. Several methods have been used to test for the presence of synergistic interactions, but virtually all are either very time consuming or nonstandardized. With combinations of cell wall-active agents plus aminoglycosides, bactericidal synergism has been associated with enhanced intracellular uptake of the aminoglycoside. Combinations of beta-lactamase inhibitors with beta-lactams susceptible to enzymatic hydrolysis have yielded synergistic activity against a number of common pathogens. The example of trimethoprim-sulfamethoxazole illustrates the potential value of combination of drugs acting at proximate steps along a single metabolic pathway. By analogy, combinations of antimicrobials active at various steps in peptidoglycan synthesis might also result in synergistic interactions. Use of certain drug combinations does pose the risk, however, of unwanted antagonistic interactions. The clinical importance of synergism in the treatment of bacterial infections has been documented in only a few limited circumstances.

Vancomycin-resistant enterococci. Mechanism and clinical relevance.

Vancomycin-resistant enterococci have spread widely throughout the United States. Mechanisms of glycopeptide resistance are understood to a significant extent. These organisms are associated with considerable morbidity. Treatment options are limited, and control of their spread requires considerable effort and results in increased costs.

Aminoglycoside resistant enterococcal endocarditis.

There are few well-documented cases of infective endocarditis due to highly aminoglycoside-resistant enterococci reported to date. Nevertheless, strains with high-level resistance to both streptomycin and gentamicin are now sufficiently common that the number of cases of endocarditis due to these organisms will undoubtedly continue to increase. Serious efforts to develop appropriate alternative treatment strategies are now clearly necessary. All high-level gentamicin-resistant bloodstream isolates from patients with suspected or proven endocarditis should be screened for high-level streptomycin resistance. Because these two resistance traits are mediated by distinct genetic elements, a significant minority of highly gentamicin-resistant enterococci will be susceptible to synergistic killing by combinations of cell wall-active antibiotics with streptomycin. For strains highly resistant to both aminoglycosides, there is no evidence of benefit from use of these toxic antimicrobials, and treatment with a cell wall-active agent alone is warranted. Based on older literature and animal models, perhaps as many as 40% to 50% of cases of enterococcal endocarditis might be curable by such regimens. Alternative combinations using a cell wall-active antibiotic together with a fluoroquinolone or rifampin cannot be specifically recommended based on any firm data from the literature, but possible merits of such combinations can be explored in vitro under appropriate circumstances. For ampicillin- and vancomycin-susceptible strains, ampicillin would seem preferable because this drug typically demonstrates greater bactericidal activity in vitro as a single agent. Consideration could be given to administration of ampicillin by continuous intravenous infusion. Several animal studies indicating effectiveness of penicillins for enterococcal endocarditis have used dosing regimens resulting in sustained serum levels. It is unknown whether these observations are relevant to human enterococcal infections. Testing for beta-lactamase production should be undertaken if penicillins are to be used. For strains that are resistant to achievable concentrations of penicillins, or when the patient is intolerant of beta-lactams, vancomycin can be used. In animal models, teicoplanin has appeared to be superior to vancomycin, but high concentrations must be attained. This drug is not yet approved for clinical use, however, and it is unclear if any advantage would exist in treatment of human infections. The recent emergence of enterococci which are resistant to glycopeptides has introduced another potential complicating factor; some of these are also substantially resistant to beta-lactams as well. In some reports, favorable interactions between vancomycin and beta-lactams have been observed against vancomycin-resistant strains.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro activity of trimethoprim alone compared with trimethoprim-sulfamethoxazole and other antimicrobials against bacterial species associated with upper respiratory tract infections.

Trimethoprim-sulfamethoxazole has been used to treat various respiratory tract infections. Nevertheless, for many patients, intolerance of the sulfonamide component precludes use of this combination. This study examined the activity of trimethoprim alone in comparison to that of trimethoprim-sulfamethoxazole and other antimicrobials against bacterial species implicated in respiratory tract infections. For Haemophilus influenzae, minimal inhibitory concentrations of trimethoprim were equal to or one dilution greater than those of trimethoprim-sulfamethoxazole, with 56 of 58 strains inhibited by the former at < or = 0.25 microgram/ml. All oxacillin-susceptible Staphylococcus aureus and 96.7% of Streptococcus pyogenes were inhibited by trimethoprim < or = 2 micrograms/ml. In contrast, only 50% of Streptococcus pneumoniae were inhibited by this concentration of trimethoprim, whereas 93.3% were susceptible to the combination at < or = 2/38 micrograms/ml. All oxacillin-resistant S. aureus and all Moraxella catarrhalis were resistant to trimethoprim, although many of the former and all of the latter were susceptible to trimethoprim-sulfamethoxazole.